Download PRELIMINARY EXPERIMENTS IN THE USE OF

PRELIMINARY EXPERIMENTS IN THE USE OF CHLORELLA AS HUMAN FOOD
Yuji Morimura and Nobuko Tamiya
The Tokugawa Institute for Biological Research, Tokyo, Japan
(Manuscript received July 17, 1953)
The use of unicellular algae such as chlorella as a food supplement is discussed, since the production of these algae
by industrial methods may be feasible. Algae powder increases as the protein and vitamin content of foods to
which it is added and palatable bread, noodles, ice cream, soups, etc., thus fortified are described. Acceptable "soy
sauce" can be prepared by processing chlorella.
Among human sensations, perhaps the most complicated and intangible are those of taste. Closely associated with
other physiological functions as well as with multifarious psychological factors, the gustatory sense is affected not
simply by the palatability of substances, but also by traditional prepossessions of individuals as well as by capricious
fads and propaganda. It is, indeed, a most difficult undertaking to introduce a new item of human food, unless its
taste and appearance are quite similar to those of other popular foods or unless it has some special nutritive or
medicinal effect without any disagreeable taste or appearance. Theoretically, we may, by proper processing,
extract palatable substances from almost all natural organic materials around us, even those that have an
abominable taste in the raw state. Obviously, however, it is the cost of processing that determines the usability of
such raw organic materials as sources of human food.
For unicellular algae to be readily acceptable as human food, they must either in the raw state or after being
processed in the simplest possible way, either have a taste, odor, and appearance that are similar to, or
reminiscent of, those of some pre-existing popular food; or have no peculiar taste, odor, or appearance, so that
they can be mixed with other foods without being noticed. We have attempted to test the usability of chlorella as
food by adding it in the raw dried state to some common foods, and also by processing it by certain simple
methods.
We will discuss the origin and nature of chlorella powder and describe some food enriched with it. The nutritional
value of its addition to bread, noodles and ice cream as well as the occurrence of vitamins, amino acids and
carbohydrates in chlorella will be listed. In addition to the direct addition of chlorella powder to foods, a processing
method for the preparation of "soy sauce" from chlorella will be described.
Material used
In most of the experiments we used dried and powered cells of Chlorella ellipsoidca which has been grown
The "urea-EH" medium described by Tamiya et al, ( . The algal cells, separated from the culture medium, were
washed once or twice with water by centrifuging, and the thick paste of cells obtained was dried at room
temperature with infrared lamps and an electric fan. The dried mass of cells as then crushed and ground to find
powder in a mortar.
The powder is dark green and a little hygroscopic. Kept in an ordinary atmosphere, it absorbs water to about 8.5 to
10% of the total weight. Its appearance is similar to, although its color is a little darker than that of the powdered
green tea which is commonly used in the traditional tea ceremony in Japan. Its taste, though not exactly the same,
is very similar to that of powdered dry "aonori" a seaweed (enteromorpha compressa) which is commonly used as
seasoning in Japanese cookery. Cells dried at temperatures lower than 15° C. have a milder taste and odor than
those dried at higher temperatures.
Addition of chlorella powder to foods
Tests were made to determine to what extent chlorella powder can be added to various common foods without
causing queer or disagreeable taste sensations. In each case, tasting was
a. Powered green tea ("hiki’cha") To powdered green tea of ordinary quality, chlorella powder can be
added without causing significant change in taste, up to as much as 20% of the total weight. To mix
well with tea powder, algal cells must be ground as finely as possible.
b. Soups
Western style. One or 2 teaspoons of chlorella powder added to bean, mushroom, or beef soup or to consomme
was excellent, but in chicken soup the taste was not so pleasant. The green color of algae is less apparent in cream
soupe than in clear ones.
Japanese style. A Japanese-style soup was prepared using not only chlorella powder and a dried seaweed, "kombu"
(Lami-naria japonica), but also a substitute "soy sauce" made of chlorella cells. (For this sauce, see a later section of
this paper.) A piece of dried "kombu" 3 ½ inches square is boiled with 4 cups of water for 3 minutes, after which ½
cup of "katsuo-bushi" flakes (flakes of dried meat of bonito), 2 tablespoons of ""sake""(Japanese rice wine) and 1½
teaspoon of sodium glutamate are added successively at 3-minute intervals. To 1 cup of the supernatant of the
above solution are added 1 or 2 teaspoons of chlorella powder, ¼ teaspoon of chlorella "soy sauce", and ¼
teaspoon of salt.
c. Noodles.
Western style. Tasty green noodles were prepared by kneading 4 teaspoons (9.4g) of chlorella powder with 1 cup
(142g) of flour, ¼ teaspoon (3.3g) of salt and ¼ cup (60ml) of water.
"Soba", a buckwheat noodle of Japanese Tele. "Soba" is one of the most popular foods in Japan and is made with 30
to 50% buckwheat flour and 70 to 50% wheat flour. By adding 2 to 5% Chlorella powder to this mixture of flours we
obtained a green noodle almost identical, both in appearance and in taste, with the so-called "cha-soba" a choice
type of "soba" containing powdered green tea as an ingredient.
d. Bread and rolls. Green-colored French bread having an interesting and agreeable taste was
prepared by adding 8 tablespoons (56g) of chlorella powder to 6 cups (852g) of white flour, the
mixture being baked in the usual way after adding 1 tablespoon (14g) of sugar, 2 teaspoons (27g) of
salt, and one yeast cake (5g dry weight)
Richer in taste were rolls prepared with the following materials: 8 tablespoons (56g) of chlorella powder, 4 cups
(568g) of flour, ½ cup (110g) of butter, 1 cup (237ml) of milk, 7 tablespoons (99g) of sugar, 2 eggs, 1 teaspoon (13g)
of salt, and one yeast cake. Addition of nuts increased the attractiveness of the rolls in taste, texture, and
appearance. Fancy looking rolls with variegated colors were prepared by layering ordinary dough alternately with
that containing chlorella.
e. Cookies. Different kinds of green-colored cookies were prepared by mixing chlorella powder with
flour. Appropriate proportions of ingredients for a simple recipe are 2 teaspoons (47g) of chlorella
powder, 2 cups (226g) of cake flour, ½ cup (114g) of sugar, ¼ pound of butter, and 1 small egg.
f. Ice cream. Surprisingly large amounts of chlorella powder can be added to ice creams. Not only is
the dark green color of the algae diluted to a pleasant light green, but also the characteristic taste
of the algae effectively accentuates the basic taste of the ice cream. To one cup of vanilla ice
cream, more than 5 teaspoons of chlorella powder may be added. The proportion of ingredients in
such an ice cream is, for example, as follows: 10 tablespoons (71g) of chlorella powder, 4 cups
(1000g) of evaporated milk, 2 cups (473ml) of milk, 1 tablespoon (89g) of flour, 1 cup (27g) of sugar,
2 eggs (98g) and 2 tablespoons (30ml) of vanilla extract.
Table 1
Estimated quantities of principal nutrient substances in some chlorella-containing foods
(The composition of chlorella cells was tekn, following Ketchum et al (1) as being 42% protein 22%
fat, 24% carbohydrate, and 12% ash, in dry weight)
Composition
(Per 100g dry Weight
Protein
(g)
Fat
(g)
CarboHydrate
(g)
Ash
(g)
Vit.A
(I.U.)
,
,
Vit.B1
(mg)
Vit B2
(mg)
French bread:
Chlorella (5.0g)
,
Wheat flour (89,3g)
Yeast (0,5g)
Sugar (1,5g)
Salt (2,8g)
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
Vit.C
(mg)
Noodles
Chlorella (6.1g)
,
Wheat flour (91,8g)
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
Salt (2,1g)
,
Ice Cream:
Chlorella (9.9g)
,
,
,
Evaporated milk (37.0g)
,
Milk (7,5g)
,
,
,
,
,
,
Flour (10,8g)
,
,
,
,
,
,
Eggs (3,4g)
,
,
,
,
,
,
Sugar (31,4g)
,
,
,
,
Table 2
Amino Acids in chlorella cells
Fractions
Amino Acids
Water Soluble
Water Insoluble
Combined
Free
Combined
Leucine
Iso-Ieucine
+++
++++
++++
Valine
++
+++
++++
Lysine
++
+++
+++
Threonine
++
+++
+++
Histidine
++
+++
++
Phenylalanine
++
++
+++
Areginine
+++
+
++
Tryptophane
--
++
++
Methionine
+
+(?)
++
Essential
Tyrosine
++
++
++
Cystine
+
+
+
Alanine
++++
++++
++++
Glycine
+++
+++
++++
Glutamic Acid
++
+++
++++
Proline
+++
+++
+++
Aspartic acid
++
++
++
Serine
++
+++
++
y-Amino-butyric acid
+++
+
++(?)
b -Alanine
+
+
++
A-Amino butyric acid
--
--
++
Citrulline
--
?
+
Unknown
+
+
+
Nonessential:
Estimated quantities of nutrient substances in chlorella containing foods
To what extent does the addition of chlorella powder increase the nutritional values of the foods
described above? Table 1 shows the estimated content of various substances in French bread
(containing 8 tablespoons of algal powder per 6 cups of flour), noodles (Western style, containing 4
teaspoons of algal powder per 1 cup of flour) and ice cream (containing 4 ½ teaspoons of algal powder
per 1 cup of ice cream)
As may be seen from these figures, additions of chlorella causes an increase of 20% in protein and 75%
in fat in the case of bread and noodles and about 30% in protein and 15% in fat in the case of ice
cream. Noteworthy is the fact that by the addition of algae the foods are made considerably richer in
vitamins A and C, which are lacking in ordinary breads and noodles. The amino acid, sugar, and vitamin
contents of the chlorella powder are given in Tables 2, 3 and 4 respectively
Some attempts at processing chlorella powder
Simple methods of processing chlorella cells are suggested by those used in processing soybeans in
Japan.
One of the most popular foods in both China and Japan is "tofu" or soybean curd, which is a clot of
proteins (called "glycinin") prepared by coagulating the water extract of soybean by the action of
magnesium or calcium salts (chlorides or sulfates). "Tofu" is white and by itself almost tasteless,
although it contains, besides easily digested proteins, some fat and carbohydrate. Its appeal as food is
largely due to it soft and delicate texture, as well as its neutrality, which permits it to harmonize with
and set off the taste of other foods mixed with it. For these reasons it is used in almost all kinds of
dishes in far Eastern countries. In the hope.of getting a "tofu"-like product, the method used with
soybeans was tested with water decoction of chlorella powder, but unfortunately, it proved totally
unsuccessful. Obviously, this failure is due to the difference in nature of the proteins contained in
different plants.
Another suggested Japanese method is that of preparing a substitute "soy sauce" by hydrolysis of soya
beans. Soy sauce is indispensable in preparing almost all kinds of Japanese foods; the authentic way of
preparing it is by fermenting steamed soybeans (together with some wheat or rich) with salt and a
mold. As pergillus oryzae.
Besides this mold, a number of bacteria and yeast’s participate in the process of fermentative
decomposition of various substances, which requires about one year for producing the typical color
and taste of soy sauce Since this method is rather complicated and time consuming, a short-cut
chemical method is now being widely used in parallel with the authentic method. They soybeans are
hydrolyzed with hydro-chloric acid which is later neutralized with sodium hydroxide or sodium
carbonate to give the appropriate amount of sodium chloride. The resulting sauce is almost identical in
appearance and taste with genuine ones, although it lacks some essential savor. To conceal this
defect, the sauce manufactured in this way is usually sold mixed with genuine soy sauce.
Using powdered chlorella cells, we attempted the chemical method of preparing a substitute for soy
sauce. One hundred g. of chlorella powder was suspended in 200ml of 25 to 20% solution of
hydrochloric acid in an Erlenmeyer flask provided with a condenser, and heated on a sand bath.
Analysis of the solution for nitrogen indicated that about hours’ heating was sufficient for they
hydrolysis to proceed to a desirable stage After to hours’ hydrolysis, the mixture was filtered and
neutralized with sodium bicarbonate to pH 4.5-5.4. The solution thus obtained was almost exactly
similar in appearance to real soy sauce, and showed the composition presented in Table 5. In this table
the composition of typical genuine soy sauce as well as the prescribed standard for commercial "soy
sauce" is also given for comparison.
Table 3
Sugars in chlorella cells
Sugar
Fractions
Water Soluble
Water Soluble
80% alcohol
insoluble
Water Insoluble
Glucose
++
+++
++
Fructose (ketcheptose)
+++
+
+++
Xylose
+++
--
+++
Galactos
++
?
++
Ribose and Ribalose
+
--
++
Triose
+
+
+
Sucrose
+
.......
--
Phosphate esters
++
.......
--
Gluconic acid
+
.......
++
Ketogluconic Acid
-
+
++
Galacturonic acid
+
.......
++
Glucuronic acid
+
.......
+
Table 4
Some vitamins fond in chlorella cells
Content per gram dry weight
Vitamin A
5000 International Units
(as provitamin)
Vitamin B1
4g
Vitamin B2
21~28g
VitaminB6
9g
Niacin
176g
Folic Acid
485g
Vitamin C
2000-5000g
Table 5
Composition of chlorella hydrolysate as compared with that of genuine soy sauce and the
standard for commercial "soy sauce"
Genuine Soy
Sauce
Chlorella
Hydrolysate
Nonaqueous
substances
Standard for commercial "soy
sauce"
-
Total Nitrogen
Amino nitrogen
-
Sodium Chloride
Specific Gravity
23.2Be
25,5 Be
.17.5 Be
When properly diluted, the hydrolysate of chlorella powder tastes almost the same as sauce prepared
from soybeans by the chemical method. The taste was considerably improved when the following sub
substances were added: lactic acid (0.2%), acetic acid (0.05%), succinic acid (0,0005%), ethanol (0.01%
and sucrose (0,05%)/
These experiments show that the preparation of a substitute for soy sauce is a very promising way of
using chlorella cells.
Taste of other unicellular algae
A few experiments conducted with dried powder of Chlorella pyrenoidosa, Emerson’s strain, showed
that it tastes almost exactly the same as the strain of C ellipsoidea we have used. We also found that
dried materials of scenedesmus, chlorococcum, and even a sea-water alga, Dunaliella salina, tastes
almost the same as chlorella. It may well be expected that the methods used with chlorella may also
be applied successfully to these different kinds of unicellular algae.
Summary
Dried powder of chlorella cells shows a taste and flavor similar to those of powered green tea and
powdered dry "aonori" a seaweed (Enteromorpha compressa) commonly used as a seasoning in
Japanese cookery. It was found that the algal powder can be added to various kinds of food, both
Western and Japanese, giving them an agreeable taste and appearance and increasing their protein,
fat, and vitamin content. An attempt at extracting a "tofu" –like material from chlorella cells failed, but
by hydrolysis of algal powder a solution was obtained which may be used as a substitute for soy sauce.
_______________________________________________________________________
a Some of the experiments reported were carried out at the Carnegie Institution of Washingtons's
Department of Plant Biology, Standford, California, Members of the Department staff assisted in
testing the products
b
Besides this seaweed, there are a number of algae, from both fresh and sea water, which are popular
in Japanese cookery. Some examples are:suizenji-nori(Phyllodorma sacumI),kawanori I(Prasiola
japonica) hitoegusa (Monostroma nitidum); makombu (Laminaria japonica) wakame (Undaria
pinnatifida), hijiki (Hijikia fusiformis)arame (Eisenia bicyclis),mozuku(Cladosiphone decipiens)
c
This kind of tea is served not as a water extract, as are other kinds of tea, but as a suspension of tea
powder in hot water, prepared by beating the mixture with a small bamboo whisk immediately before
serving. The somewhat bittersweet taste of raw young tea leaves is much enjoyed by Japanese people,
but does not appeal to most Western people.